KR20140003202A - Powder coating method and powder coated film manufactured thereby - Google Patents

Abstract

The present invention relates to a powder coating method and a powder coated film manufactured thereby. The powder coating method includes the following steps of: arranging an object to be coated; performing a preconditioning process of the surface of the object to be coated; spraying coating powder on the preconditioned object; performing a first thermal process and a second thermal process by using microwaves after the spraying step; and cooling down the object. A corrosion prevention effect of an object is made by removing the possibility of fault of coating powder and increasing the efficiency of a coating since the preconditioning step is performed before the step for spraying the coating powder in order to increase the surface cleanliness of the object. A color formation is also improved by optimizing the thermal process steps and increasing the adhesiveness of the coating powder. Moreover, the coating powder with improved quality provided by the power coating method of the present invention is useful for a facility maintenance work, a painting work, a coating work, a construction work, a shipbuilding work, a vehicle work, an ocean plant, a pipeline work, an agricultural implement work, a hospital, and a defense industry. [Reference numerals] (AA) Powder ring hanging process; (S1) Step for preparing an object to be coated; (S2) Step for preconditioning the surface of the object to be coated; (S21) Chemical bath dipping; (S22) Chapeau process; (S3) Step for spraying coating powder; (S4) Step for a thermal process; (S41) First thermal process; (S42) Second thermal process; (S5) Step for cooling

Description

Powder coating method and powder coating film manufactured therefrom {POWDER COATING METHOD AND POWDER COATED FILM MANUFACTURED THEREBY}

The present invention relates to a powder coating method and a powder coating film prepared therefrom, and more particularly, by performing a surface pretreatment step of a coating material, thereby improving surface cleanliness, eliminating coating defects, and increasing the efficiency of coating to realize an anti-rust effect of the coating material. In addition, the present invention relates to a powder coating method and a powder coating film prepared therefrom which have improved color development by improving the adhesion of powder coating by optimizing the heat treatment step.

Generally, corrosion of steel is caused by iron ionization due to inhomogeneity of steel itself and inhomogeneity of external environment.

In particular, in the case of corrosion in reinforced concrete, the ion chlorine through the cracks in the concrete (Cl ^-) various primary defect or chambers Province of breaking the concrete, the chloride ion due to non-uniformity of the car, such as a salt with an alkali concentration (Cl ^- Diffusion of) destroys the passivation film on the surface of the reinforcement, or due to chemical non-uniformity of the steel surface, the potential of the steel surface becomes macroscopically non-uniform, resulting in an anode and a cathode. Will cause corrosion.

Corrosion of steel proceeds as follows.

2Fe → 2Fe ²⁺ + 4e ^- (ionized iron)

_{O 2 + 2H 2 O + 4e} - → 4OH - ( occurs in healthy iron parts)

4Fe + O ₂ + 2H ₂ O → 2Fe (OH) ₂ (produce ferrous hydroxide)

4Fe (OH) ₂ + O ₂ + 2H ₂ O → 4Fe (OH) ₃ (Generation of ferric hydroxide)

When the resulting compound continues to lose moisture and becomes ferric hydroxide (red rust), some become Fe ₃ O ₄ (black rust) with insufficient oxidation to form a layer of rust.

Therefore, in the case of all metals, since corrosion proceeds when contacted with air, a method of blocking contact with air is mentioned as a rust prevention technique.

For example, the method of treating grease or oil on a metal surface is typical, but this method does not function as the grease or oil hardens on the surface during long-term storage, and moisture-containing air penetrates through the minute gaps, thereby There is a drawback to partial rust.

Therefore, there is an urgent need for a rust prevention technology capable of long term rusting for about 1 to 5 years in poor adverse conditions or outdoors. In particular, small and medium-sized companies that export metal-processed products to other countries have poor market competitiveness due to deterioration of product quality due to rust problems, and in particular, in the EU, they are limited by environmental standards (ROHS). This is a problem that must be solved.

In an effort to remedy this problem, there is a commercially available product line of rust inhibitors / coated rust inhibitors (RUS-601 rust inhibitors).

These rust inhibitors / coating rust preventives prevent structural degradation by preventing rust on metal surfaces such as reinforcing bars, and are resin-coated rust preventives that form a thick rustproof coating by curing after chemical reactions with moisture. It aims to fundamentally block the oxidation of iron from moisture and oxygen by forming a protective film.

As a form of other commercial products, the rust remover / rust convertor (RUS-605) is a groundbreaking method that automatically removes rust within 24 hours by simply spraying it onto a metal surface. After removal, the product is converted into a high molecular compound to form a stable passivation film. Thus, the rust remover / rust conversion agent is easy to maintain the iron essence, there is no problem in the secondary process such as painting or rust preventive after rust removal, rather it serves to improve the adsorptive power during protective coating work. The rust remover / rust conversion agent is a rust removal conversion agent that returns adhesion to concrete to a state before rust generation, and exhibits a rust prevention effect of about 2 to 3 months after rust removal.

Another type of commercial product is rust preventives, which form a protective film on the metal surface for the desired period of time to prevent rust. Generally, various rust inhibitors such as sulfonates are applied to petroleum bases, and oil, grease, and solid phases are possible. In addition, there are vaporization rust inhibitors and plastic rust inhibitors.

Recently, functional packaging papers (vaporizable films, vaporizable wraps, vaporizable rust preventives) using vaporizable rust inhibitors have been released.

However, as for the materials related to the rust prevention of steel, many researches and product launches have been conducted, but research and development for implementing corrosion resistance of the coated surface are needed from the method of coating the powder.

In general, powder coating is a process in which fine powder is evenly sprayed on the surface to be coated and melted when heated to apply powder coating, and the strength of the coating site is strong and the surface is smooth.

In addition, since the powder coating is a powder, storage or transportation is economical because the glass and the paint can be recovered and reused, and the coating process can be shortened, thereby saving energy. At this time, the average coating thickness is about 60㎛ and excellent corrosion resistance, adhesion, durability, etc. than the conventional solvent type (liquid paint), in particular, excellent corrosion protection. Therefore, powder coating is recognized as the best eco-friendly painting technology in existence.

However, in order to apply powder coating, it is necessary to be equipped with an oven facility and a special coating machine, which entails a place limit. In addition, the cleaning time of the coating booth is much longer than that of the solvent coating, even in the case of a single color or color change. Formation of a thin film has a problem that is difficult.

In particular, the success or failure of the powder coating depends on the surface cleanliness of the coating, if the process is improved to remove the coating defects and to increase the efficiency of the coating, it is possible to implement the anti-corrosive effect of the coating in the powder coating process.

Accordingly, the present inventors have made efforts to improve the conventional problems, and as a result, by optimizing a specific pretreatment process and a heat treatment process after the coating before the coating of the coating in the powder process to confirm that the present invention by improving the anti-rust effect of the final coating, Completed.

It is an object of the present invention to provide a powder coating method which improves the quality of powder coating film by performing a pretreatment step of the coating material and optimizing the heat treatment step after powder coating.

Another object of the present invention is to provide a powder coating film as an excellent antirust and antirust effect prepared from the powder coating method.

In order to achieve the above object, the present invention provides a preparation step; Surface pretreatment of the workpiece; Powder coating spraying the surface pretreated coating material; Performing a first heat treatment and a second heat treatment using microwaves after the spraying step; It provides a powder coating method comprising a; and a cooling step.

In the powder coating method of the present invention, the surface pretreatment step refers to an immersion treatment for 30 seconds to 10 minutes in a solution tank containing an organic chlorine solvent, and at this time, the solution tank containing the organic chlorine solvent is maintained at a temperature of 90 to 115 ℃ It is characterized by.

In addition, the surface pretreatment step of the present invention may be additionally performed a pretreatment step in which the chaff step of the front surface of the workpiece is further performed.

Subsequently, the surface-treated workpiece is fixed to the powder hanger to perform a powder coating spraying step.

In the powder coating method of the present invention, a first heat treatment and a second heat treatment step of the surface sprayed with the powder coating are carried out, wherein the first heat treatment step is 5 seconds to 30 at a temperature of 180 to 210 ℃ by microwave emission lamp irradiation Is done for seconds.

In addition, the second heat treatment is performed at 180 to 210 ° C. for 5 to 30 minutes, thereby providing high fixation and color development during powder processing.

Furthermore, in the powder coating method of the present invention, after the heat treatment step, the reducing gas is discharged through the ventilation apparatus installed in the lower layer of the heat treatment machine, thereby preventing reattachment of fine particles or fine dust inside the machine.

Accordingly, the present invention is obtained from the powder coating method, and provides a powder coating film having an antifouling or anti-rust effect.

In the powder coating method of the coating of the present invention, by performing a pretreatment step of the coating, to improve the surface cleanliness of the coating to eliminate the coating defects and to increase the efficiency of the coating to achieve the anti-rust effect of the coating.

In addition, in the powder coating method of the coating of the present invention, by optimizing the heat treatment step after the powder coating spraying step, it is possible to increase the adhesion of the powder coating to improve the color development.

Accordingly, the powder coating method of the present invention is applied to facility maintenance management, paint industry, painting industry, construction industry, shipbuilding industry, automobile industry, offshore plant, pipeline industry, agricultural equipment industry, hospital, defense industry, etc. Powder coating film can be provided.

Figure 1 shows a process flow diagram of the powder coating method of the present invention,
Figure 2 is a surface photograph of the powder coating film subjected to the first heat treatment and the second heat treatment step of the powder coating method of the present invention.

Hereinafter, the present invention will be described in detail.

1 shows a process flow chart of the powder coating method of the present invention, specifically,

The present invention is to be coated (皮 塗 物) preparing step (S1);

Surface pretreatment of the workpiece (S2);

Powder coating spraying step (S3) of the surface pretreated coating;

Performing a first heat treatment and a second heat treatment using microwaves after the spraying step (S4); And

It provides a powder coating method comprising a cooling step (S5).

The coating preparation step (S1) of the present invention includes all the material surface that is applied to the general powder coating field as coarse sand or fine chaff material. In addition, the workpiece may be prepared by polishing rusty products, removing oil, removing impurities, and removing paper. The prepared workpiece may be further shortened and sanded again.

The pretreatment step (S2) of the present invention is a step (S21) of immersion treatment in the solution bath containing the organic chlorine-based solvent before the coating material prepared above is powder coating.

At this time, the solution bath containing the organic chlorine-based solvent is preferably maintained at a temperature of 90 to 115 ℃, and expands and expands a part of the surface of the coating to easily remove dust, tea, oil, etc., to improve the transparency of the product smooth surface Can be obtained.

If the temperature of the solution bath is less than 90 ℃ in the above, the oil and blemish removal effect is low, under the conditions exceeding 115 ℃ there is a problem that the production cost increases, which is not preferable. That is, when the solution bath temperature of the pretreatment step exceeds 115 ℃, it is difficult to carry out high temperature in the field, the equipment is large and additional costs are generated, it is difficult to apply practically.

In addition, the immersion time is preferably 30 seconds to 10 minutes, more preferably is carried out for 10 minutes at the temperature of the solution bath 100 ℃. At this time, if the immersion time is less than 30 seconds, the transparency and smoothness of the product due to the immersion in the pretreatment solution can not be expected, if more than 10 minutes, the production cost increases due to the reduction in energy costs and output.

In the powder coating method of the present invention, the surface of the coating material varies depending on the temperature of the solution bath in the pretreatment step. However, when the solution bath temperature is performed at 60 ° C., the oily tea is insufficiently removed. The surface is found to be relatively smooth and with less coating bonds.

The organic chlorine solvent used in the pretreatment process of the present invention may include trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane (methylchloroform), and the like in the embodiment of the present invention. Ethylene (TCE) is described as an example, but is not limited thereto.

The solution tank containing the organic chlorine solvent may contain 0.1 to 0.3 parts by weight of sodium nitrite (NaNO ₂ ) based on 100 parts by weight of the organic chlorine solvent. At this time, the sodium nitrite may improve the absorbency of the final product of the powder coating due to the nature of absorbing moisture in the air. At this time, if the content of sodium nitrite is less than 0.1 parts by weight, the color development is lowered, which is not preferable, and if it exceeds 0.3 parts by weight, there is a problem that the color changes.

By performing only the above pretreatment process alone, or after performing the pretreatment process, by further performing the shapo process on the entire surface of the workpiece (S22), it is possible to optimize the clean antifouling effect.

The present invention can increase the transparency of the target surface by 10 to 20%, improve the antifouling properties and smoothness by pre-treating the surface of the coating before the powder coating, it is possible to reduce the content of the powder coating.

By maximizing the surface cleanliness of the coating, it is possible to eliminate coating defects and increase the efficiency of painting, and further increase the Rust-Zero rust prevention effect of the powder coating obtained from the powder coating method.

In the powder coating method of the present invention, the coating material, which has undergone the pretreatment step, is individually fixed to the main body ring and sprayed with powder coating.

Therefore, through the process of hanging the powder ring, to prevent dust contamination from the ground, and to wear the anti-fingerprint gloves to powder coating separately, it is possible to produce the outer surface of the powder product itself, and to reduce the drug As a result, production costs and raw material costs can be lowered, and further, product life or product quality can be increased.

Then, the powder coating spray step (S3) of the present invention is carried out, it can be applied by appropriately shortening the coating material fixed to the powder ring. At this time, the component / content of the powder coating used in the powder coating spraying step and the method applied to the spraying step include conventionally used methods such as spray gun, constant voltage powder coating, and electric deposition.

In the embodiment of the present invention, the constant voltage powder spray method is described as an example, but is not limited thereto.

In the heat treatment step (S4) of the present invention, after the first heat treatment (S41) is performed in order to increase the adhesion of the coated object coated with powder in the above step, the color development property is performed, the second heat treatment (S42) is performed.

In this case, the first heat treatment step S41 uses microwaves, that is, frequencies of 2000 to 2400 MHz (wavelength: 1 mm to 1 μm) of microwaves used in the electron lens.

At this time, the first heat treatment step condition is to irradiate for 5 to 30 seconds using a black electric lamp that emits microwaves. At this time, the applied temperature of the coating is 180 to 210 ℃ temperature range. At this time, if the irradiation time is less than 5 seconds, the expected effect due to irradiation is insufficient, and if it exceeds 30 seconds, productivity decreases.

Thereafter, the second heat treatment S42 is performed at 180 to 210 ° C. for 5 to 30 minutes. At this time, when the second heat treatment temperature is lower than 180 ° C., the curing time of the hot melt resin is short, so that durability and adhesive strength are lowered. On the other hand, when the heat treatment temperature exceeds 210 ° C, the color of the powder processed product becomes yellowish, and the color becomes dark.

In addition, the heat treatment time depends on the thickness of the powder product. If the thickness is thick, it is 5 to 30 minutes, more preferably 5 to 10 minutes. In this case, when the second heat treatment step is performed in less than 5 minutes, the powder processed product has a problem of lowering the quality of the product due to low friction strength and surface strength, and when the heat treatment time exceeds 30 minutes, the powder processed product is yellow. The color of the product becomes dark.

Figure 2 is a surface photograph of the powder coating film subjected to the first heat treatment and the second heat treatment step of the powder coating method of the present invention, without coating defects, by confirming the clean surface shape with a rust agent, it is possible to implement an excellent antifouling and anti-rust effect .

In the powder coating method of the present invention, when the heat treatment step is completed, passing through the cooling step (S5), it is carried out along the natural cooling rail or fixedly mount the workpiece after the heat treatment step in a manner of lowering the ambient temperature. .

In addition, the powder coating method of the present invention focuses on the non-volatile gas, unsaturated gas or heavy reducing gas generated in the heat treatment machine after the heat treatment step sinks to the bottom of the heat treatment, the ventilating device in the lower layer of the heat treatment machine The installation may further perform the step of exhausting the reducing gas.

More specifically, a 25m / m pipe is placed on the bottom edge of the heat treatment machine and a 2m / m size hole is sucked into the suction type ventilator to discharge heavy reducing gas.

As described above, by discharging and removing the non-volatile gas, unsaturated gas or reducing gas, the color development of the final powder coating film is increased, yellowing of the powder coating film is prevented, and the surface is prevented from being uneven due to contamination due to teeing and dust. .

In addition, by preventing reattachment due to fine powder and fine dust inside the heat treatment machine, the color of the powder coating film is increased, and the color development of 15-25% of the product quality is improved.

Powder coating method of the present invention may further perform a quality inspection step and packaging step of the powder coating film, such as removing the powder-coated product from the conveyor belt, scratching the coating surface, the degree of dusting and nonuniformity of the powder after the natural cooling step. .

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

≪ Example 1 >

A solution bath in which sodium nitrite 1000 mg / L (0.1 parts by weight) was mixed with respect to trichloroethylene (TCE) and 100 parts by weight of the TCE solvent was prepared. The solution bath was maintained at 115 ° C., and the coating material was immersed in the solution bath for 1 minute and then dried. The pretreated workpiece was fixed by hanging on a powder ring. At this time, the workpiece is shortened and fixed in size to favor the working conditions. Subsequently, the powder coating was sprayed on the entire surface with an electric constant voltage on the surface of the workpiece.

The sprayed coated object caught in the powder ring was transferred to a heat treatment machine room maintained at a temperature of 190 ° C. along the conveyor belt, and irradiated for 10 seconds using an electric black lamp (Sankyo, BLB 1-2 kW). According to the transfer direction in the heat treatment machine room, when the heat treatment is completed, the heat treatment was continuously performed for 5 minutes at 210 ℃ temperature.

At this time, the 25m / m pipe was laid on the corner of the bottom surface of the heat treatment machine room during the heat treatment step, and the reducing gas was discharged through the 2m / m size hole.

When the heat treatment step is completed, it passed through the heat treatment machine room and naturally cooled at room temperature along the rail and dried. When the drying was completed, the product was removed from the conveyor belt and packaged through product quality steps.

≪ Example 2 >

The same process as in Example 1 was carried out except that the temperature of the pretreatment solution bath containing trichloroethylene was 90 ° C.

≪ Comparative Example 1 &

The same process as in Example 1 was carried out except that the temperature of the pretreatment solution bath containing trichloroethylene was 60 ° C.

Comparative Example 2

The same process as in Example 1 was performed except that the first electrothermal treatment step was not performed.

<Experimental Example 1>

The surfaces of the coatings passed through Examples 1 and 2 and Comparative Examples 1 and 2 were visually compared. As a result, in the case of Comparative Example 1 in which the bath temperature was 60 ° C., the surface of the surface of the object to be carried out at the solution bath temperature of 115 ° C. was relatively relatively free, while the surface of the surface of the workpiece under the bath temperature of 115 ° C. was relatively removed. Smooth and less coating bond. From the above result, the optimum temperature of the pretreatment liquid was set.

<Experimental Example 2>

The surfaces of the powder coating films prepared through the steps of Example 1 and Comparative Example 2 were compared.

FIG. 2 is a surface of the powder coating film prepared in Example 1, which is free from defects in the coating film, and confirms a clean surface shape with a dissolving agent.

As described above, the present invention provides a preparation step; Surface pretreatment of the workpiece; Powder coating spraying the surface pretreated coating material; Performing a first heat treatment and a second heat treatment using microwaves after the spraying step; And it provides a powder coating method comprising a; cooling step.

Powder coating method of the present invention by performing the pre-treatment step of the coating material, to improve the surface cleanliness of the coating material to eliminate the coating defects and to increase the efficiency of the coating to realize the rust prevention effect of the coating, by optimizing the heat treatment step after the powder coating spray step, It can improve the color development by increasing the adhesion of powder coating.

The powder coating method of the present invention is applied to facility maintenance management, paint industry, painting industry, construction industry, shipbuilding industry, automobile industry, offshore plant, pipeline industry, agricultural equipment industry, hospital, defense industry, etc. where powder coating is required. It is possible to provide a powder coating film with excellent dissolution agent.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (9)

Preparation of the object;
Surface pretreatment of the workpiece;
Powder coating spraying on the surface pretreated coating;
Performing a first heat treatment and a second heat treatment using microwaves after the spraying step; And
Powder coating method comprising a cooling step. The powder coating method according to claim 1, wherein the surface pretreatment step is immersed for 30 seconds to 10 minutes in a solution bath containing an organochlorine solvent. The powder coating method according to claim 2, wherein the solution bath containing the organic chlorine solvent is maintained at a temperature of 90 to 115 ° C. The powder coating method according to claim 2, wherein the surface pretreatment step further includes a shaping process on the entire surface of the workpiece. The powder coating method according to claim 1, wherein the surface pretreated coating is fixed to a powder hanger, and then powder coating spraying is performed. The powder coating method according to claim 1, wherein the first heat treatment is performed at a temperature of 180 to 210 ° C. for 5 seconds to 30 seconds by microwave emission lamp irradiation. The powder coating method according to claim 1, wherein the second heat treatment is performed at 180 to 210 ° C for 5 to 30 minutes. The powder coating method according to claim 1, wherein after the heat treatment step, the reducing gas is discharged through an air vent installed in the lower layer of the heat treatment machine. The powder coating film which implemented the antirust effect with the rust agent manufactured from the powder coating method of any one of Claims 1-8.

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